 /*
  * $Header: /cvshome/build/org.osgi.framework/src/org/osgi/framework/PackagePermission.java,v 1.14 2006/06/16 16:31:18 hargrave Exp $
  *
  * Copyright (c) OSGi Alliance (2000, 2006). All Rights Reserved.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  * http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */

 package org.osgi.framework;

 import java.io.IOException ;
 import java.security.*;
 import java.util.Enumeration ;
 import java.util.Hashtable ;

 /**
  * A bundle's authority to import or export a package.
  *
  * <p>
  * A package is a dot-separated string that defines a fully qualified Java
  * package.
  * <p>
  * For example:
  *
  * <pre>
  * <code>
  * org.osgi.service.http
  * </code>
  * </pre>
  *
  * <p>
  * <code>PackagePermission</code> has two actions: <code>EXPORT</code> and
  * <code>IMPORT</code>. The <code>EXPORT</code> action implies the
  * <code>IMPORT</code> action.
  *
  * @version $Revision: 1.14 $
  */

 public final class PackagePermission extends BasicPermission {
     static final long serialVersionUID = -5107705877071099135L;
     /**
      * The action string <code>export</code>.
      */
     public final static String EXPORT = "export";

     /**
      * The action string <code>import</code>.
      */
     public final static String IMPORT = "import";

     private final static int ACTION_EXPORT = 0x00000001;
     private final static int ACTION_IMPORT = 0x00000002;
     private final static int ACTION_ALL = ACTION_EXPORT
                                                             | ACTION_IMPORT;
     private final static int ACTION_NONE = 0;
     /**
      * The actions mask.
      */
     private transient int action_mask = ACTION_NONE;

     /**
      * The actions in canonical form.
      *
      * @serial
      */
     private String actions = null;

     /**
      * Defines the authority to import and/or export a package within the OSGi
      * environment.
      * <p>
      * The name is specified as a normal Java package name: a dot-separated
      * string. Wildcards may be used. For example:
      *
      * <pre>
      * org.osgi.service.http
      * javax.servlet.*
      * *
      * </pre>
      *
      * <p>
      * Package Permissions are granted over all possible versions of a package.
      *
      * A bundle that needs to export a package must have the appropriate
      * <code>PackagePermission</code> for that package; similarly, a bundle
      * that needs to import a package must have the appropriate
      * <code>PackagePermssion</code> for that package.
      * <p>
      * Permission is granted for both classes and resources.
      *
      * @param name Package name.
      * @param actions <code>EXPORT</code>,<code>IMPORT</code> (canonical
      * order).
      */

     public PackagePermission(String name, String actions) {
         this(name, getMask(actions));
     }

     /**
      * Package private constructor used by PackagePermissionCollection.
      *
      * @param name class name
      * @param mask action mask
      */
     PackagePermission(String name, int mask) {
         super(name);
         init(mask);
     }

     /**
      * Called by constructors and when deserialized.
      *
      * @param mask action mask
      */
     private void init(int mask) {
         if ((mask == ACTION_NONE) || ((mask & ACTION_ALL) != mask)) {
             throw new IllegalArgumentException ("invalid action string");
         }

         action_mask = mask;
     }

     /**
      * Parse action string into action mask.
      *
      * @param actions Action string.
      * @return action mask.
      */
     private static int getMask(String actions) {
         boolean seencomma = false;

         int mask = ACTION_NONE;

         if (actions == null) {
             return (mask);
         }

         char[] a = actions.toCharArray();

         int i = a.length - 1;
         if (i < 0)
             return (mask);

         while (i != -1) {
             char c;

             // skip whitespace
 while ((i != -1)
                     && ((c = a[i]) == ' ' || c == '\r' || c == '\n'
                             || c == '\f' || c == '\t'))
                 i--;

             // check for the known strings
 int matchlen;

             if (i >= 5 && (a[i - 5] == 'i' || a[i - 5] == 'I')
                     && (a[i - 4] == 'm' || a[i - 4] == 'M')
                     && (a[i - 3] == 'p' || a[i - 3] == 'P')
                     && (a[i - 2] == 'o' || a[i - 2] == 'O')
                     && (a[i - 1] == 'r' || a[i - 1] == 'R')
                     && (a[i] == 't' || a[i] == 'T')) {
                 matchlen = 6;
                 mask |= ACTION_IMPORT;

             }
             else
                 if (i >= 5 && (a[i - 5] == 'e' || a[i - 5] == 'E')
                         && (a[i - 4] == 'x' || a[i - 4] == 'X')
                         && (a[i - 3] == 'p' || a[i - 3] == 'P')
                         && (a[i - 2] == 'o' || a[i - 2] == 'O')
                         && (a[i - 1] == 'r' || a[i - 1] == 'R')
                         && (a[i] == 't' || a[i] == 'T')) {
                     matchlen = 6;
                     mask |= ACTION_EXPORT | ACTION_IMPORT;

                 }
                 else {
                     // parse error
 throw new IllegalArgumentException ("invalid permission: "
                             + actions);
                 }

             // make sure we didn't just match the tail of a word
 // like "ackbarfimport". Also, skip to the comma.
 seencomma = false;
             while (i >= matchlen && !seencomma) {
                 switch (a[i - matchlen]) {
                     case ',' :
                         seencomma = true;
                     /* FALLTHROUGH */
                     case ' ' :
                     case '\r' :
                     case '\n' :
                     case '\f' :
                     case '\t' :
                         break;
                     default :
                         throw new IllegalArgumentException (
                                 "invalid permission: " + actions);
                 }
                 i--;
             }

             // point i at the location of the comma minus one (or -1).
 i -= matchlen;
         }

         if (seencomma) {
             throw new IllegalArgumentException ("invalid permission: " + actions);
         }

         return (mask);
     }

     /**
      * Determines if the specified permission is implied by this object.
      *
      * <p>
      * This method checks that the package name of the target is implied by the
      * package name of this object. The list of <code>PackagePermission</code>
      * actions must either match or allow for the list of the target object to
      * imply the target <code>PackagePermission</code> action.
      * <p>
      * The permission to export a package implies the permission to import the
      * named package.
      *
      * <pre>
      * x.y.*,&quot;export&quot; -&gt; x.y.z,&quot;export&quot; is true
      * *,&quot;import&quot; -&gt; x.y, &quot;import&quot; is true
      * *,&quot;export&quot; -&gt; x.y, &quot;import&quot; is true
      * x.y,&quot;export&quot; -&gt; x.y.z, &quot;export&quot; is false
      * </pre>
      *
      * @param p The target permission to interrogate.
      * @return <code>true</code> if the specified
      * <code>PackagePermission</code> action is implied by this
      * object; <code>false</code> otherwise.
      */

     public boolean implies(Permission p) {
         if (p instanceof PackagePermission) {
             PackagePermission target = (PackagePermission) p;

             return (((action_mask & target.action_mask) == target.action_mask) && super
                     .implies(p));
         }

         return (false);
     }

     /**
      * Returns the canonical string representation of the
      * <code>PackagePermission</code> actions.
      *
      * <p>
      * Always returns present <code>PackagePermission</code> actions in the
      * following order: <code>EXPORT</code>,<code>IMPORT</code>.
      *
      * @return Canonical string representation of the
      * <code>PackagePermission</code> actions.
      */

     public String getActions() {
         if (actions == null) {
             StringBuffer sb = new StringBuffer ();
             boolean comma = false;

             if ((action_mask & ACTION_EXPORT) == ACTION_EXPORT) {
                 sb.append(EXPORT);
                 comma = true;
             }

             if ((action_mask & ACTION_IMPORT) == ACTION_IMPORT) {
                 if (comma)
                     sb.append(',');
                 sb.append(IMPORT);
             }

             actions = sb.toString();
         }

         return (actions);
     }

     /**
      * Returns a new <code>PermissionCollection</code> object suitable for
      * storing <code>PackagePermission</code> objects.
      *
      * @return A new <code>PermissionCollection</code> object.
      */
     public PermissionCollection newPermissionCollection() {
         return (new PackagePermissionCollection());
     }

     /**
      * Determines the equality of two <code>PackagePermission</code> objects.
      *
      * This method checks that specified package has the same package name and
      * <code>PackagePermission</code> actions as this
      * <code>PackagePermission</code> object.
      *
      * @param obj The object to test for equality with this
      * <code>PackagePermission</code> object.
      * @return <code>true</code> if <code>obj</code> is a
      * <code>PackagePermission</code>, and has the same package name
      * and actions as this <code>PackagePermission</code> object;
      * <code>false</code> otherwise.
      */
     public boolean equals(Object obj) {
         if (obj == this) {
             return (true);
         }

         if (!(obj instanceof PackagePermission)) {
             return (false);
         }

         PackagePermission p = (PackagePermission) obj;

         return ((action_mask == p.action_mask) && getName().equals(p.getName()));
     }

     /**
      * Returns the hash code value for this object.
      *
      * @return A hash code value for this object.
      */

     public int hashCode() {
         return (getName().hashCode() ^ getActions().hashCode());
     }

     /**
      * Returns the current action mask.
      * <p>
      * Used by the PackagePermissionCollection class.
      *
      * @return Current action mask.
      */
     int getMask() {
         return (action_mask);
     }

     /**
      * WriteObject is called to save the state of this permission object to a
      * stream. The actions are serialized, and the superclass takes care of the
      * name.
      */

     private synchronized void writeObject(java.io.ObjectOutputStream s)
             throws IOException {
         // Write out the actions. The superclass takes care of the name
 // call getActions to make sure actions field is initialized
 if (actions == null)
             getActions();
         s.defaultWriteObject();
     }

     /**
      * readObject is called to restore the state of this permission from a
      * stream.
      */
     private synchronized void readObject(java.io.ObjectInputStream s)
             throws IOException , ClassNotFoundException {
         // Read in the action, then initialize the rest
 s.defaultReadObject();
         init(getMask(actions));
     }
 }

 /**
  * Stores a set of <code>PackagePermission</code> permissions.
  *
  * @see java.security.Permission
  * @see java.security.Permissions
  * @see java.security.PermissionCollection
  */

 final class PackagePermissionCollection extends PermissionCollection {
     static final long serialVersionUID = -3350758995234427603L;
     /**
      * Table of permissions.
      *
      * @serial
      */
     private Hashtable permissions;

     /**
      * Boolean saying if "*" is in the collection.
      *
      * @serial
      */
     private boolean all_allowed;

     /**
      * Create an empty PackagePermissions object.
      */

     public PackagePermissionCollection() {
         permissions = new Hashtable ();
         all_allowed = false;
     }

     /**
      * Adds a permission to the <code>PackagePermission</code> objects. The
      * key for the hash is the name.
      *
      * @param permission The <code>PackagePermission</code> object to add.
      *
      * @throws IllegalArgumentException If the permission is not a
      * <code>PackagePermission</code> instance.
      *
      * @throws SecurityException If this
      * <code>PackagePermissionCollection</code> object has been marked
      * read-only.
      */

     public void add(Permission permission) {
         if (!(permission instanceof PackagePermission))
             throw new IllegalArgumentException ("invalid permission: "
                     + permission);
         if (isReadOnly())
             throw new SecurityException ("attempt to add a Permission to a "
                     + "readonly PermissionCollection");

         PackagePermission pp = (PackagePermission) permission;
         String name = pp.getName();

         PackagePermission existing = (PackagePermission) permissions.get(name);

         if (existing != null) {
             int oldMask = existing.getMask();
             int newMask = pp.getMask();
             if (oldMask != newMask) {
                 permissions.put(name, new PackagePermission(name, oldMask
                         | newMask));

             }
         }
         else {
             permissions.put(name, permission);
         }

         if (!all_allowed) {
             if (name.equals("*"))
                 all_allowed = true;
         }
     }

     /**
      * Determines if the specified permissions implies the permissions expressed
      * in <code>permission</code>.
      *
      * @param permission The Permission object to compare with this
      * <code>PackagePermission</code> object.
      *
      * @return <code>true</code> if <code>permission</code> is a proper
      * subset of a permission in the set; <code>false</code>
      * otherwise.
      */

     public boolean implies(Permission permission) {
         if (!(permission instanceof PackagePermission))
             return (false);

         PackagePermission pp = (PackagePermission) permission;
         PackagePermission x;

         int desired = pp.getMask();
         int effective = 0;

         // short circuit if the "*" Permission was added
 if (all_allowed) {
             x = (PackagePermission) permissions.get("*");
             if (x != null) {
                 effective |= x.getMask();
                 if ((effective & desired) == desired)
                     return (true);
             }
         }

         // strategy:
 // Check for full match first. Then work our way up the
 // name looking for matches on a.b.*

         String name = pp.getName();

         x = (PackagePermission) permissions.get(name);

         if (x != null) {
             // we have a direct hit!
 effective |= x.getMask();
             if ((effective & desired) == desired)
                 return (true);
         }

         // work our way up the tree...
 int last, offset;

         offset = name.length() - 1;

         while ((last = name.lastIndexOf(".", offset)) != -1) {

             name = name.substring(0, last + 1) + "*";
             x = (PackagePermission) permissions.get(name);

             if (x != null) {
                 effective |= x.getMask();
                 if ((effective & desired) == desired)
                     return (true);
             }
             offset = last - 1;
         }

         // we don't have to check for "*" as it was already checked
 // at the top (all_allowed), so we just return false
 return (false);
     }

     /**
      * Returns an enumeration of all <code>PackagePermission</code> objects in
      * the container.
      *
      * @return Enumeration of all <code>PackagePermission</code> objects.
      */

     public Enumeration elements() {
         return (permissions.elements());
     }
 }

